In answer to your question, it depends on how much detail you want. We do one Passage Cartridge that covers the whole of the UK and French coast between Dover, Brest and the Scilly isles which costs £115 + VAT and includes 150,000 scale charts for the whole area and 75,000 scale charts of The Solent, Dartmouth and Dover.
Many people new to electronic charting go for this cartridge as a cost effective way of covering a large area and in conjunction with their existing paper charts and pilot books is a very good solution.
If you want full coverage of this area including all of the detailed harbour and port plans, then you are probably talking about 3-4 cartridges at £115 + VAT each to cover from Falmouth to Selsey Bill across to Cherbourg and West to L'Aberwrach.
I suggest you have a look at our website www.c-map.co.uk for more information or let us know where your boat is and we can arrange for you to have a demonstration of the cartridges at one of our local dealers.
So often, we complain about the poor service offered by companies. By contrast, I have found that C-Map UK offer friendly and prompt after sales service. They have on more than one accasion provided me with technical support and software upgrades for my Vision chart plotter at no cost. Another company I've recently found to be pretty good is Raytheon. So well done Raytheon and particularly Paul Sumpner of C-Map.